diff --git a/services/message-delivery-method-web-push/generate-keys.js b/services/message-delivery-method-web-push/generate-keys.js
index 85251a3..2838d9c 100644
--- a/services/message-delivery-method-web-push/generate-keys.js
+++ b/services/message-delivery-method-web-push/generate-keys.js
@@ -1,6 +1,10 @@
 import webpush from "web-push";
 import PouchDB from "./PouchDB.js";
 
+if (!process.env.VAPID_SUBJECT) {
+  throw new Error('VAPID_SUBJECT env is empty!');
+}
+
 const vapidKeys = webpush.generateVAPIDKeys();
 
 await new PouchDB(`${process.env.API_URL}/server_settings`, {